This invention relates to a method for improving cardiac function. More particularly, this invention relates to an intrapericardial assist procedure. The invention is useful in assisting a patient""s heart in its pumping function, even where there is congestive heart failure. This invention also relates to a method for assisting a patient""s heart in its pumping function.
When a patient""s heart stops, for example, in the operating room, cardiopulmonary resuscitation (CPR) is required. In that procedure the chest is violently pounded at the region of the sternum to compress the chest and thereby compress the heart between the sternum and the spine. This compression forces blood out of the ventricles through the one-way valves of the heart. When the pressure on the heart is released, the heart expands and blood is sucked into the heart.
For all its violence, CPR is a delicate procedure in that it must be performed correctly in order to have the desired result of starting the stopped heart. A problem with CPR is that, whether or not it is performed correctly, CPR invariably results in cracked ribs, a fractured sternum and destroyed costo-chondral (cartilage) junctions. Thus even if a patient survives CPR, he is usually injured.
Another serious cardiac condition arises in people who have experienced heart attacks. In such persons, a portion of the heart muscle is frequently destroyed by the attack. Although nerves passing through the damaged heart tissue are not destroyed to the point of ceasing function, the operation of the nerves may be significantly impaired. Conduction of nerve impulses may be delayed. This delay in signal transmission over the impaired nerves results in a delay in heart muscle contraction in those parts of the heart controlled by the impaired nerves. This condition is observed as a xe2x80x9cbundle branch blockxe2x80x9d in an electrocariogram.
Reviving a patent after cardiac arrest is made more difficult when the patient suffers from congestive heart failure. Congestive heart failure occurs, inter alia, where there has been a heart attack or an infection. In either case, the pumping action of the heart is impaired. In another malfunction, left ventricular hypertrophy, the myocardium of the left ventricle becomes thickened to the point of interfering with effective heart contraction. Hypertrophy of the left ventricular muscle arises from a sticky heart valve or aortic stenosis. The increase in left ventricular pressure resulting from increased resistance to blood flow out of the left ventricle gradually induces an increase in the size of the myocardium about the left ventricle. This left ventricular hypertrophy is a dangerous condition, particularly where the individual suffers from coronary artery disease. The larger heart muscle requires greater blood flow and is therefore more sensitive to even temporary reductions in that flow. Such a reduction in blood flow occurs, for example, when the afflicted individual exercises.
A surgical procedure for treating congestive heart failure, developed by a doctor in Brazil, involves removing a triangular portion of a patient""s heart. In this operation, approximately one-third of the patient""s left ventricular muscle is removed. The result is that the smaller heart pumps more efficiently. This technique of course requires open heart surgery, with its attendant expense and extended convalescence.
An object of the present invention is to provide a method and/or an associated device for assisting cardiac function.
A more particular object of the present invention is to provide such a method and/or device which is less traumatic than conventional cardiac treatment techniques.
Another particular object of the present invention is to provide such a method and/or device wherein the device is implanted into the heart or the intrapericardial space.
A further object of the present invention is to provide such a method and/or device which can compensate for or take into account congestive heart failure.
It is another object of the present invention to provide a such method taking into account congestive heart failure which may be carried out through the use of minimally invasive procedures.
An additional object of the present invention is to provide a device for implementing such a surgical method.
Another object of the present invention is to provide such a method and/or device which is of simple construction.
A further, more particular, object of the present invention is to provide such a method and/or device which is implemented at least partially automatically.
These and other objects of the present invention will be apparent from the drawings and detailed descriptions herein. It is to be noted that although every embodiment of the invention is believed to meet one or more of the stated objectives, not every object is necessarily attained in every embodiment of the invention.
The present invention is directed to a surgical method for assisting cardiac function. Generally, the method comprises an at least partial closure of a lower portion of at least one ventricle of a patient""s heart. Optionally, the method also includes applying compressive force to the patient""s heart via a balloon inserted into an intrapericardial space about the heart.
Pursuant to one embodiment of the present invention, the method includes inserting a device into a patient and applying the device to a lower end portion of the patient""s heart so as to compress and at least partially close a lower portion of at least one ventricle of the heart. The device includes a wire provided at a free end with at least one anchoring barb. The applying of the device to the lower portion of the patient""s heart includes inserting a catheter into a ventricle of the patient""s heart and ejecting the free end of the wire from the catheter into the patient""s myocardium so that the free end and the at least one barb are embedded in the myocardium, surrounded thereby. Tension is exerted on the wire to pull walls of the patient""s heart towards one another so as to compress and close off the lower portion of the at least one ventricle of the heart.
In a more particular execution of the method of the present invention, the free end of the wires is one of a pair of free wire ends each provided with at least one barb, while the applying of the device to the lower portion of the patient""s heart includes ejecting the free wire ends from the catheter into the patient""s myocardium so that the free ends and the respective barbs thereof are embedded in the myocardium, surrounded thereby. Tension is exerted on the wire ends to pull the walls of the patient""s heart towards one another so as to compress and close off the lower portion of the at least one ventricle of the heart.
Pursuant to another feature of the present invention, the wire ends are terminal portions of wire segments and the exerting of tension on the wire ends includes twisting the wire segments about one another.
Where the walls targeted by the wire ends are outer walls of the patient""s heart, the applying of the device serves to compress and at least partially close lower portions of two ventricles. Where one of the walls is an outer wall of the patient""s heart while another of the walls is a septum of the patient""s heart, the applying of the device serves to compress and at least partially close a lower portion of exactly one ventricle. In this latter case, the ejecting the free end of the wire from the catheter into the patient""s myocardium may include forcing the free end of the wire through the septum of the patient and into the outer wall of the patient""s heart.
The method may further comprise inserting at least one balloon into an intrapericardial space about the patient""s heart and inflating the balloon in the intrapericardial space to place a compressive pressure on the patient""s heart sufficient to force blood from the heart. Generally, the wire device is applied to the lower portion of the patient""s heart prior to the inflating of the balloon. In addition, the method possibly comprises periodically inflating and alternately deflating the balloon to pump blood from the heart in pulsatile fashion. The wire device is maintained in the patient""s heart to keep the lower portion of the one or two ventricles of the patient""s heart compressed and closed off during the periodic inflating and deflating of the balloon.
In accordance with a further feature of the present invention, the inserting of the balloon into the intrapericardial space includes providing a hypodermic type needle, inserting the needle through a skin surface and into the intrapericardial space, and injecting the balloon in a collapsed configuration into the intrapericardial space.
Where the balloon has an arcuate cuff configuration in an inflated configuration, the inflating of the balloon includes shaping the balloon into the arcuate configuration.
Thus, the wire device of the present invention may be deployed in a minimally invasive, intravascular procedure. Alternatively, the wire device may be inserted through a trocar sleeve or cannula.
A method for reducing ventricular volume comprises, in accordance with another embodiment of the present invention, inserting a catheter into a ventricle of a patient""s heart, deploying a tensile member from a leading end of the catheter, attaching the tensile member to the patient""s heart so that the tensile member is contained completely within the patient""s heart and does not protrude therefrom, and exerting tension on the tensile member to draw walls of the patient""s heart towards one another to reduce the volume of at least one ventricle of the patient""s heart. The tensile member may be provided with at least one barb at a leading end, the attaching of the tensile member to the patient""s heart including embedding the barb in the patient""s heart. Where the tensile member is one of two tensile members, the method further comprises attaching the other tensile member to the patient""s heart, the exerting of tension on the one of the tensile members including twisting the tensile members about one another. As discussed above, the walls drawn together by the tensile may be outer walls of the patient""s heart, so that the attaching of the tensile member to the patient""s heart and the exerting tension on the tensile member serve to compress and at least partially close lower portions of two ventricles. Alternatively, the walls drawn together by the tensile may be an outer wall of the patient""s heart and a septum of the patient""s heart, so that the attaching of the tensile member to the patient""s heart and the exerting tension on the tensile member serve to compress and at least partially close a lower portion of exactly one ventricle.
In some embodiments of the present invention, the compressive or tensile member may take the form of an elongate tack ejected from a tubular member such a catheter or trocar sleeve or cannula.
It is apparent, therefore, that the present invention is directed in part to a method for reducing ventricular volume, wherein a catheter is inserted into a ventricle of a patient""s heart, a cardiac insert or implant is deployed from a leading end portion of the catheter, and the cardiac insert or implant is disposed in the patient""s heart to reduce the volume of one or two ventricles of the patient""s heart. The cardiac insert or implant is preferably applied to the lower or apical end of the heart. It is contemplated that the cardiac insert or implant takes the form of a tensile member such as a wire or tack which is attached to the patient""s heart. However, other forms of inserts or implants may be effective to reduce ventricular volume.
A surgical method in accordance with the present invention treats congestive heart failure. The method may be performed thoracoscopically which is less expensive and less traumatic to the patient than an open-heart surgical technique. The minimally invasive, intravascularly implemented procedure is even less expensive and less traumatic to the patient. The method of the invention is simple and reliable.
A surgical method in accordance with the present invention provides assistance for cardiac function and may utilize a balloon which is initially in a collapsed configuration. The balloon together with an implantable tensile device is inserted into a patient inside the pericardium. More particularly, the balloon is positioned in the intrapericardial space. The secondary device is employed to close off the lower end portion of one or both of the patient""s ventricles, the balloon being used to contract or compress the remaining portion of the patient""s heart to squeeze blood from the reduced-size ventricle(s).
A method in accordance with the present invention is capable of compensating for differential action of an individual""s heart. The method and device are effective when a chamber of the individual""s heart experiences excessive pressure levels owing, for example, to a sticky valve or aortic stenosis.